Abstract
We report the growth of gallium-based compounds, i.e., gallium oxynitride (GaON) and gallium oxide (Ga2O3) on multilayer graphene (MLG) on insulator using a mixture of ammonium nitrate (NH4NO3) and gallium nitrate (Ga(NO3)3) by electrochemical deposition (ECD) method at room temperature (RT) for the first time. The controlling parameters of current density and electrolyte molarity were found to greatly influence the properties of the grown structures. The thicknesses of the deposited structures increase with the current density since it increases the chemical reaction rates. The layers grown at low molarities of both solutions basically show grain-like layer with cracking structures and dominated by both Ga2O3 and GaON. Such cracking structures seem to diminish with the increases of molarities of one of the solutions. It is speculated that the increase of current density and ions in the solutions helps to promote the growth at the area with uneven thicknesses of graphene. When the molarity of Ga(NO3)3 is increased while keeping the molarity of NH4NO3 at the lowest value of 2.5 M, the grown structures are basically dominated by the Ga2O3 structure. On the other hand, when the molarity of NH4NO3 is increased while keeping the molarity of Ga(NO3)3 at the lowest value of 0.8 M, the GaON structure seems to dominate where their cubic and hexagonal arrangements are coexisting. It was found that when the molarities of Ga(NO3)3 are at the high level of 7.5 M, the grown structures tend to be dominated by Ga2O3 even though the molarity of NH4NO3 is made equal or higher than the molarity of Ga(NO3)3. When the grown structure is dominated by the Ga2O3 structure, the deposition process became slow or unstable, resulting to the formation of thin layer. When the molarity of Ga(NO3)3 is increased to 15 M, the nanocluster-like structures were formed instead of continuous thin film structure. This study seems to successfully provide the conditions in growing either GaON-dominated or Ga2O3-dominated structure by a simple and low-cost ECD. The next possible routes to convert the grown GaON-dominated structure to either single-crystalline GaN or Ga2O3 as well as Ga2O3-dominated structure to single-crystalline Ga2O3 structure have been discussed.
Highlights
The performance of silicon ultra-large-scale integrated circuits (Si-ULSIs) has been enhanced over the last 30 years by increasing the number of transistors in accordance with Moore’s law [1]
We report the direct growth of Ga-based compound materials on graphene on insulator by an electrochemical deposition
First, the chemical reactions that are expected to take place during the growth need to be formulated in order to predict the possible grown structures
Summary
The performance of silicon ultra-large-scale integrated circuits (Si-ULSIs) has been enhanced over the last 30 years by increasing the number of transistors in accordance with Moore’s law [1]. The scaling rule of the Si transistor has made it possible to miniaturize the transistors in the Si-ULSIs. the miniaturization of the Rashiddy Wong et al Nanoscale Research Letters (2015) 10:233 fabricate various kinds of functional devices, such as optical devices [4], photodetectors [5], solar batteries [6], and so forth. In order to be able to fabricate electronic devices in those semiconductor materials, it is necessary to electronically isolate such materials and the Si substrate by the conventional insulators such as silicon dioxide (SiO2) or silicon nitride (Si3N4). Some breakthrough on growth technologies is strongly required to realize high-quality semiconductor-on-insulator on Si structures
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